Add feature flag for scalable app list

BUG=976947

Change-Id: I1fe1788345a4dcdb0f155cc3283995c2336e6607
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1774878
Commit-Queue: Toni Baržić <[email protected]>
Reviewed-by: Xiyuan Xia <[email protected]>
Cr-Commit-Position: refs/heads/master@{#691429}
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index fd79e35..ccf813e 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -1658,6 +1658,13 @@
     "Enables an experiment to switch menu labels that use 'Save as...' to "
     "'Download'.";
 
+const char kScalableAppListName[] =
+    "App list UI configuration dependant on display size";
+const char kScalableAppListDescription[] =
+    "Adapts app list item sizing and spacing for smaller screen sizes, "
+    "instead of using single app list configuration, that is optionally "
+    "scaled down, for all screens.";
+
 const char kScrollableTabStripName[] = "Scrollable TabStrip";
 const char kScrollableTabStripDescription[] =
     "Allows users to access tabs by scrolling when they no longer fit in the "